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Completed

NCT Number: NCT05534893

Effect of Blueberries on Immunity

This research study will test the effects of Blueberries on immune functions in overweight older men and postmenopausal women

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Key information

Conditions

Immune Response Inflammation Pathologic Processes Pathological Conditions, Signs and Symptoms

Age range

50 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Loma Linda University School of Public Health

Loma Linda, California, 92350, United States

About this study

This study will examine the effects of Blueberries on clinically relevant markers of immune function. Eligible and selected participants will be randomized to one of two groups at the baseline clinic visit. The Blueberry group participants will consume blueberries (2 packets of blueberry freeze-dried powder equivalent to 2 cups of fresh blueberries) added to the habitual diet and the Control group participants will abstain from blueberries (with instructions to limit the consumption of other berries and polyphenol rich foods) but otherwise continue their habitual diet. During the study, clinic visits will occur at 4-week intervals (baseline, weeks 4, 8 and 12) for a total of 4 visits at the Loma Linda University Nutrition Research Center. Blood samples taken at baseline and at week 12 will be assayed for changes in immune function and inflammatory markers.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Older men and post-menopausal women aged 50-70 year
  • Have BMI of 25-32
  • Able to commute to Loma Linda University
  • Consuming a typical American Diet low in polyphenols

Exclusion criteria

  • Intolerance or allergy to Blueberries
  • Regular intake of Blueberries and other berried (>2 ounces/week)
  • Immune system insufficiency or disease
  • Using immune boosting supplements
  • Exposure to antibiotics and corticoids immediately prior to study
  • Uncontrolled chronic diseases and relevant psychiatric illness, including major depression
  • Flu vaccination and or Covid Vaccination less than 3 months ago from the start of the study

Treatment and study plan

Blueberry powder group

Dietary Supplement

Participants in the blueberry powder group will receive freeze dried blueberries in form of a powder

Placebo powder group

Dietary Supplement

Participants in the placebo powder group will receive an isocaloric placebo powder

Primary outcomes

  1. changes in lymphocyte populations

    Time frame: baseline to 12 weeks

    Immunophenotyping will be performed by flow cytometry to measure the number of T helper, T cytotoxic, Naïve and memory cells and B cells

  2. changes in cytokine production

    Time frame: baseline to 12 weeks

    PBMC cells will be separated from blood, activated and cultured using phytohemagglutinin (PHA). Inflammatory cytokine production will be measured in the resulting supernatant using ELISA

  3. changes in natural killer (NK) cell activity

    Time frame: baseline to 12 weeks

    The NK degranulation assay will be performed on blood samples. The test will be conducted using a modified flow cytometry method that measures the expression of CD107a

  4. changes in serum inflammatory cytokine concentration

    Time frame: baseline to 12 weeks

    Changes in the concentrations of the inflammatory cytokines will be performed on serum using enzyme-linked immunoassay (ELISA)

  5. changes in complete blood count (CBC)

    Time frame: baseline to 12 weeks

    changes in the complete blood count will be performed on whole blood with the use of an automated hematology analyzer at a certified clinical facility

Sponsors and collaborators

Lead sponsor

Loma Linda University

Other

Collaborators

  • U.S. Highbush Blueberry Council

Registry information

Official study title

Immune Benefits of Blueberry Consumption in Overweight Older Men and Postmenopausal Women: A Randomized Trial

Acronym: Blueberry

Important dates

Study start
2022
Primary completion
2023
Study completion
2023
First posted
Sep 10, 2022
Registry last updated
Feb 4, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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